Many medical conditions are treated by the implantation of a prosthesis in a body lumen. Such conditions include vascular stenosis and aneurysms and such prosthesis include stents and stent grafts. Increasingly, such prosthesis are deployed by endoluminal transport from a site remote from the deployment site. Fixation of the prosthesis at the deployment site is necessary to avoid displacement of the prosthesis. Stents are elongated devices, typically of a tubular skeletal metallic structure, with substantial elasticity. Stents may be used to support intraluminal walls and to exert a radial force on a constricted portion of a lumen wall to open a lumen to near normal size.
A stent-graft typically includes tubular graft material affixed to the inside or outside of a stent and is delivered to the damaged site of a blood vessel via a catheter. Endoluminal stent-grafts, i.e. stent grafts delivered endoluminally, are often used to repair blood vessels affected by a variety of lesions such as stenoses or aneurysms. In the case of a stenosis, a stent provides an unobstructed conduit for blood, by-passing a diseased area of the vessel.
Once deployed in a body lumen, such as a blood vessel, stents and stent grafts have a tendency to move. Such movement may be caused by fluid flow at the deployment site and/or by changing body morphology. In the case of a stent graft, this may lead to leakage around the stent graft.
In some situations, such as in the case of abdominal aortic aneurysums (AAA) this problem is acerbated by the presence of diseased tissue at or near the end of the stent graft, near the renal arteries for example. In view of the foregoing, it would be desirable to have a more positive way of effectively retaining prostheses, such as stents and stent-grafts, particularly in a region of diseased tissue, and thereby more effectively preventing movement of the prosthesis and leakage around an end thereof.